1. Field of the Invention
The present invention relates to a bonding method, a bonding stage, and an electronic component packaging apparatus that includes this bonding stage. In particular, the present invention relates to a bonding method, a bonding stage, and an electronic component packaging apparatus that packages electronic components such as a semiconductor chip on a substrate in a plasma atmosphere.
Priority is claimed to Japanese application No. 2002-281071, filed Sep. 26, 2002, which is incorporated herein by reference.
2. Description of Related Art
As is shown, for example, in Japanese Patent Application Laid-Open (JP-A) No. 64-61923, the apparatus shown in FIG. 4 is known as a semiconductor chip packaging apparatus that includes a conventional bonding stage.
In FIG. 4, the descriptor 100 is a semiconductor chip packaging apparatus. This semiconductor chip packaging apparatus 100 is supported by a supporting column 132 standing on a base 130 such that an ultrasonic oscillator 134 is able to be raised and lowered freely in the directions indicated by the arrows in FIG. 4. A semiconductor chip adhesion device 136 is mounted on a distal end of the ultrasonic oscillator 134, and a semiconductor chip 180 is able to be adhered to and held by a bottom end of the semiconductor chip adhesion device 136.
A table 138 used for position adjustment is provided on a top surface of the base 130, and a heater 140 is provided on a top surface of the position adjustment table 138. As is shown in FIG. 5A, a circuit substrate 141 is placed and held on a top surface of the heater 140. A predetermined circuit pattern 120 is formed on the circuit substrate 141, and bumps 116 are formed connecting to the circuit pattern 120.
In order to perform packaging by bonding using this type of semiconductor chip packaging apparatus 100, firstly, the relative positions of the semiconductor chip 180 and the circuit substrate 141 are adjusted by the position adjustment table 138.
Next, the bumps 116 are heated by the heater 140 to a temperature at which they will melt. At the same time, as is shown in FIGS. 5B and 5C, the ultrasonic oscillator 134 is lowered and ultrasonic oscillation is applied so that thermocompression bonding is achieved at a predetermined pressure. A cooling process is then performed. As a result, the semiconductor chip 180 and the circuit substrate 141 that packages the semiconductor chip 180 are bonded via the bumps 116.
As is described, for example, in JP-A No. 11-340614, a known method for connecting electronic components such as semiconductor devices to circuit substrates is a bonding method that includes a step in which oxide film formed on the surfaces of the bumps is removed, a step in which the bumps are left in a predetermined environment for a predetermined time so that a reoxide film is formed on the bump surfaces, and a step in which the bumps are heated, melted and then allowed to harden so that bonding is achieved. In this method, a method of removing the oxide film using sputtering based on plasma processing is disclosed.
Furthermore, as is disclosed, for example, in JP-A No. 2001-308144, a flip chip packaging method is known in which the surfaces of lead-free, tin-zinc based bumps are improved by an irradiation of hydrogen-containing plasma. A fluorine-containing layer is then formed on the bump surfaces using fluorine-containing plasma so as to prevent reoxidation of the bumps, and the bumps are then heated and melted, resulting in bonding being achieved.
However, in the above described semiconductor chip packaging apparatus 100 and in the electronic component bonding method, because it is necessary to heat the bumps to a temperature at which they will melt, for example, approximately 250 to 550° C., and to then rapidly cool them, the problems exist that throughput of the packaging of electronic components such as semiconductor chips is poor, and the bonding efficiency is unsatisfactory.
Moreover, in the semiconductor chip packaging apparatus 100, the temperature distribution of the heater 140 may not necessarily be uniform, so that unmelted bumps also exist. Accordingly, the problem occurs of it not being possible to perform packaging that provides a high yield and high reliability, and this also generates unsatisfactory bonding efficiency.
The present invention was conceived in order to solve the above described problems in the conventional technology, and it is an object thereof to provide a bonding method, bonding stage, and electronic component packaging apparatus that make possible packaging that provides; a high yield and high reliability at a lower temperature that does not require bumps to be heated to melting temperature, and to thereby improve the throughput of electronic component packaging, and improve bonding efficiency.